Relative Motion of Lazy River#

A child, A, floats down the lazy river, at a constant speed of $params.v_{A}Bm/s$ relative to the swimmer B, who is swimming in a straight line at a constant speed of $params.v_{B}m/s$ relative to a stationary observer on the pool deck. Both swimmers are viewed in the horizontal plane. In the above figure, $\theta \mathrm{\_}1=params.theta1$, $\theta \mathrm{\_}2=params.theta2$, $d\mathrm{\_}1=params.d1$, and $d\mathrm{\_}2=params.d2$. Note that the line between $\theta \mathrm{\_}1$ and $\theta \mathrm{\_}2$ is parallel to the y-axis.